Types of Investigations and Research Design

You need to know about several different research techniques, when they are used, and the strengths and weaknesses of each.

This table outlines different methods used in research:

Research method: Description:
Correlation Statistical technique - measures strength of relationship between variables.
Experiment An independent variable is manipulated while others controlled, to see effects on a dependent variable.
Interview Used to gain in-depth information and individual views.
Naturalistic observation Watching behaviour, as it occurs spontaneously, in a natural setting.
Questionnaire survey A snapshot of large number of people's attitudes, opinions or behaviour.

The aim of an investigation is its general purpose.

What are you trying to achieve in the investigation?

The hypothesis is a precise, testable statement or prediction about the expected outcome of an investigation.

A 'null hypothesis' (Ho) prediction is one that states results are due to chance and are not significant in terms of supporting the idea being investigated.

For example:

There is no evidence that there is a difference between groups in the amount they remember.

A research hypothesis (H1) prediction is one that states that results are not due to chance and that they are significant in terms of supporting the idea being investigated.

For example:

There is evidence that there is a difference between groups in the amount they remember.

A one-tailed hypothesis is a directional hypothesis.

For example:

Instead of saying there will be a difference between groups in the amount they remember, you predict which group will remember most.

A two-tailed hypothesis is one in which the direction of results is not predicted.

For example:

You may predict a difference between groups, but have no idea which way the difference will fall.

Remembering the difference between one and two tailed hypotheses:

A one-tailed cat can only point its tail in one direction at a time!

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A two-tailed cat can point its tail in both directions at once - it does not tell you the way things will go - it is non-directional!

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The following factors are important to consider when designing an investigation:

A pilot study is a test run on a few participants this enables you to check for design faults before carrying out an investigation on a larger scale, this is a routine procedure especially used when carrying out questionnaire.

Reliability of results is very important, so if a study is replicated the findings should be similar.

Validity, does a test measure what it was designed to measure. For example, do IQ tests really measure 'intelligence'?

Internal validity, extent to which study is free of design faults, which may affect results.

Ecological validity this is a type of 'external validity'. This means the extent to which generalisation can be made from the test environment to other situations.

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